Tooth whitening dental tray and method of use

ABSTRACT

A dental tray with a hydrophobic tooth whitening formulation where the tooth whitening formulation is substantially non-water soluble, and a method of using this dental tray to whiten the teeth. The tooth whitening formulation is primarily comprised of a hydrophobic polymer and a peroxide or a peroxide yielding compound. Preferably the hydrophobic polymer is the condensation product of a silicone resin and an organosiloxane. The dental tray is formed to encompass the front and the rear surfaces of the teeth. The dental tray is comprised of a thermoplastic or thermoset polymer. The teeth whitening formulation is placed into the dental tray and the tray placed against the teeth to be whitened. This is for a sufficient period of time to at least partially whiten teeth. This can be a period of time from about 0.5 hour to 2 hours or more. The substantially non-aqueous tooth whitening formulation is effective over a longer period of time since it is not significantly diluted or removed from the dental tray during the treatment time.

This invention relates to a dental tray and formulation for toothwhitening. More particularly this invention relates to a substantiallynon-water soluble tooth whitening formulation in a dental try and itsuse for tooth whitening.

BACKGROUND OF THE INVENTION

There is a general desire for people to have white teeth. Such whiteteeth are an indication of a good health and in particular good oralcare health. A problem is that various foods and the use of tobacco willdiscolor teeth. Beverages such as coffee, tea and cola beverages candiscolor teeth.

As a result various products and procedures have been developed towhiten teeth. These products and procedures are either purchased and/orused directly by the consumer or are applied by a dentist or otherprofessional. The more effective products and procedures are those thatare performed by a dental professional.

Typically this consists of the dental professional forming a dental trayfrom an impression of a persons teeth. The dental tray is formed by anyby any of the well known and well used procedures. After the dental trayis formed to the structure of the teeth a whitening formulation isplaced in the tray and the tray placed into the mouth and against theteeth to be treated. The tray with the whitening composition in home usetypically is left in the mouth for from about 10 minutes to severalhours; i.e. up to 12 or more hours. If the treatment is only in thedental office the time of the treatment typically will be from about 0.5hour to about 2 hours.

The products used solely by consumers primarily comprise whiteningstrips and brush-on products. Whitening strips are plastic strips withthe whitening formulation on one surface. The surface with the whiteningformulation is pressed against ones teeth and left in contact with theteeth for about 30 minutes. The plastic strip then is removed. Thebrush-on products are painted into teeth and the user keeping his/hermouth at least partially open for up to about a minute until theformulation dries onto the teeth. In both cases saliva will dilute andflush the tooth whitening composition from the user's teeth. This ismore so with strips since foreign materials, such as a plastic strip,will enhance saliva flow in the mouth. These are useful products toremove some tooth staining. However, they are not as effective as theuse of dental trays, and in particular the use of dental trays by dentalprofessionals.

A problem with the various whitening compositions that are used indental trays is that they are substantially soluble in water and saliva.This results in a dilution of the whitening formulation during use. Inorder to overcome this problem producers of these whitening formulationshave increased the concentration of the whitening actives. However, thiscauses a problem of increased tooth sensitivity, gum irritation and thepotential long term for lesions. Another solution disclosed in U.S. Pat.No. 5,846,058 has been to use higher viscosity tooth whiteningcompositions. This increases dilution time and flush time but is not afull solution to the problem. A better solution to this problem is touse a carrier and actives that are substantially insoluble in water andsaliva, the carrier being about fully insoluble in water and saliva. Theactive must have some solubility in order to attack and remove toothstains. However this should be at a low level. In this way toothwhitening compositions with a lower concentration of active can be usedto enhance whitening through a longer contact time at a more sustainedactive concentration.

BRIEF DESCRIPTION OF THE INVENTION

The dental tray can be formed from essentially any thermoplastic orthermoset polymer. The only requirement is that preferably it should beat least partially flexible to better fit into the mouth and against theteeth to be treated with the tooth whitening composition. The toothwhitening composition to be placed into the dental tray will be asubstantially non-water and non-saliva soluble composition. The majorcomponents of this tooth whitening composition will comprise anon-aqueous hydrophobic polymer and a peroxide whitening agent; andoptionally components such as an adhesive enhancing agent, surfactant,flavor and peroxide activator. Other optional materials such assubstances with antiseptic and medicinal properties also can be a partof the tooth whitening composition. This tooth whitening compositionwill have a viscosity of about 50,000 cps to about 900,000 cps, andpreferably about 200,000 cps to about 600,000 cps.

This tooth whitening composition is placed in the dental tray and thedental tray applied to the teeth to be treated. The tray is left inplace for about 0.25 hour to about 4 hours and preferably from about 0.5hour to about 2 hours. After removal the person may rinse his/her mouth.

After the treatment with the tooth whitening composition the teeth canbe treated with a tooth desensitizing formulation. This can be via useof the tray for more severe conditions to the use of a desensitizingtoothpaste for several days. Such formulations will contain potassiumnitrate, citric acid, citric acid salts, strontium chloride and thelike. A process of a first step tooth whitening procedure followed by atooth desensitizing procedure is preferred for persons who aresusceptible to tooth sensitivity problems.

DETAILED DESCRIPTION OF THE INVENTION

The present invention will be described in more detail with reference tothe preferred embodiments. However, modifications can be made to thesepreferred embodiments and be within the disclosed concept.

The dental tray can be of any conventional form and formed fromconventionally used thermoplastic polymers. Thermoset polymers also canbe used. Consequently the tray can range from highly flexible to a lowflexibility. The thermoplastic polymers are highly preferred and thosethat can be used include polyethylene and polypropylene polymers theirderivatives and copolymers, silicone elastomers, polyurethanes andderivatives, polycaprolactams, polystyrene and derivatives,polybutadiene and derivatives, polyisoprene and derivatives, andpolymethacrylate and its derivatives. These can be in a sheet, foam or alaminate form. In forming the trays a cast is taken of the teeth and gumarea of a patient and set. A thermoplastic polymer film is placed overthe cast and vacuum formed to the shape of the teeth and gum margin ofthe patient. This is now in the shape of a tray that can contain awhitening formulation and be used to treat the patients teeth.

The term “hydrophobic” polymer or “water-insoluble” polymers as employedherein refers to an organic polymer which is substantially non-aqueoushaving a water solubility of less than one gram per 100 grams of waterat 25 C. Any such polymers that are compatible with peroxide compoundsor peroxide yielding compounds and which can produce a tooth whiteningcomposition having a viscosity of about 1000 cps to about 900,000 cps,and preferably about 10,000 cps to about 100,000 cps can be used.

The composition of the present invention is a viscous suspension whichmaintains its consistency during storage enabling the product to bepainted on the tooth surface through the use of a dental tray. Thecomposition is comprised of a hydrophobic polymer that is the primarycarrier for the active whitening component which preferably is aperoxide containing or peroxide yielding compound. A preferred class ofhydrophobic polymers are silicone based polymers. There are othercomponents such as adhesion enhancing agents, flavors, sweeteningagents, surfactants, anti-microbial agents, anti-inflammatory agents,plaque buffers, vitamins, anti-caries agents, anti-plaque agents,desenticizing agents, coloring agents, pigments and opacifying agents.

The tooth whitening composition will have the following general formula:

Component Content Hydrophobic Polymer   1 to 80 wt % Adhesive EnhancingAgent   0 to 20 wt % Peroxide Whitening Agent 0.5 to 50 wt % Surfactant  0 to 50 wt % Flavor  0.1 to 1 wt % Other Components (can be HOH)   0to 10 wt %

In accordance with the practice of the present invention the hydrophobicpolymer compositions in which a peroxide can be dispersed are known inthe art and many are commercially available. The preferred siliconebased hydrophobic polymers are produced by condensing a silicone resinand an organosiloxane such as a polydiorganosilioxane. The hydrophobicpolymers are an elastomeric, tacky material, adhesion of which to dentalenamel surfaces can be varied by altering the ratio of silicone resin topolydiorganosiloxane in the copolymer molecule. For example hydrophobicpolymers available from the Dow-Corning Company under the brand nameBIO-PSA are pressure sensitive hydrophobic polymers specificallydesigned for pharmaceutical use and are permeable to many drug compoundsand find application for the transdermal application of variouscompounds. The BIO-PSA silicone polymers are the copolymer product ofmixing a silanol terminated polydiorganosiloxane such as polydimethylsiloxane with a silanol-containing silicone resin whereby the silanolgroups of the polydiorganosiloxane undergo a condensation reaction withthe silanol groups of the silicone resin so that thepolydiorganosiloxane is lightly crosslinked by the silicone resin (thatis, the polydiorganosiloxane chains are bonded together through theresin molecules to give chain branching and entanglement and/or a smallamount of network character) to form the silicone hydrophobic polymers.A catalyst, for example an alkaline material such as ammonia, ammoniumhydroxide or ammonium carbonate can be mixed with the silanol-terminatedpolydiorganosiloxane and the silicone resin to promote this crosslinkingreaction.

By copolymerizing the silicone resin with the silanol terminatedpolydiorganosiloxane, there results a polymer with self adheringproperties and the cohesive properties of a soft elastomer matrixcharacteristic of pressure sensitive polymers being distinguished fromthe hard, non-elastomeric properties of other silicone resins.

Modifying the silicone resin to polydiorganosiloxane ratio will modifythe tackiness of the hydrophilic polymer. This ratio can be in the rangeof about 70:30 to about 50:50. For example, the BIO PSA silicone sold byDow-Corning is available in three silicone resin to silicone polymerratios namely, 65/35 (low tack), 60/40 (medium tack), 55/45 (high tack).This is available dissolved in either ethyl acetate solvent ordimethicone.

The silicone based hydrophobic polymer is present in the liquidwhitening compositions of the present invention at a concentration ofabout 1 to about 80% by weight and preferably about 15 to about 40% byweight.

Organic materials which may be included in the compositions of thepresent invention to enhance the properties of the hydrophobic polymersof the present invention include adhesion enhancing agents such as waxesinclusive of bees wax, mineral oil, plastigel, (a blend of mineral oiland polyethylene), petrolatum, white petrolatum, shellac, versagel(blend of liquid paraffin, butene/ethylene/styrene hydrogenatedcopolymer) polyethylene waxes, microcrystalline waxes, polyisobutene,polyvinyl pyrrolidone/vinyl acetate copolymers, and insolublepolyacrylate copolymers. Also effective as adhesion enhancing agents areliquid hydrophilic polymers including polyethylene glycols, nonionicpolymers of ethylene oxide having the general formula:

HOCH₂(CH₂OCH₂)_(n)CH₂OH

wherein n represents the average number of oxyethylene groups.Polyethylene glycols available from Dow Chemical are designated by anumber such as 200, 300, 400, 600, 2000 which represents the approximateaverage molecular weight of the polymer, as well as nonionic blockcopolymer of ethylene oxide and propylene oxide of the formula:

HO(CH₄O)_(a)(C₃H₆O)_(b)(C₂H₄O)_(c)H

The block copolymer is preferably chosen (with respect to a, b and c)such that the ethylene oxide constituent comprises from about 65 toabout 75% by weight, of said copolymer molecule and the copolymer has anaverage molecular weight of from about 2,000 to about 15,000 with thecopolymer being present in the liquid tooth whitening composition insuch concentration that the composition is liquid at room temperatures(23° C.).

A particularly desirable block copolymer for use in the practice of thepresent invention is available commercially from BASF and designatedPluraflo L1220 which has an average molecular weight of about 9,800. Thehydrophilic poly(ethylene oxide) block averages about 65% by weight ofthe polymer.

Typically, adhesion enhancing polymers employed in the compositions ofthe invention are present in an amount of from about 0 to 20% by weight.Preferably, the polymers are present in an amount of from about 2 toabout 15% by weight.

Peroxide releasing compounds useful in the practice of the presentinvention include peroxide containing compounds such as urea peroxide,sodium percarbonate, sodium perborate and PVP-H₂0₂ complexes(hereinafter “PVP-H₂0₂”). PVP-H₂0₂ both linear and cross linkedcomplexes are known to the art and are disclosed in U.S. Pat. No.3,376,110 and U.S. Pat. No. 3,480,557 and have been used in compositionsfor treating acne vulgaris (U.S. Pat. No. 5,122,370). PVP-H₂0₂ complexesare disclosed in U.S. Pat. No. 5,122,370. PVP-H₂0₂ is stable in ananhydrous environment. By exposure to aqueous environments, as in theoral cavity, the PVP-H₂0₂ dissociates into individual species (PVPpolymer and H₂0₂). The PVP-H₂0₂ complex is generally comprised of about80% by weight polyvinyl pyrrolidone and 20% by weight H₂0₂. It also maybe useful to have as a part of the peroxide component an agent toenhance the release of peroxide. Polypore® which is an allylmethacrylate crosspolymer available from Amcol health & BeautySolutions, Inc. is such an enhancing agent.

The peroxide releasing compound is present in the liquid whiteningcompositions of the present invention at a concentration of about 0.5 toabout 50% by weight and preferably about 10 to about 40% by weight.

Nonionic surfactants which are compatible with peroxide compounds serveas a solubilizing, dispersing, emulsifying and wetting agents and areespecially effective to solubilize a flavor if included in the liquidwhitening composition. A particularly useful nonionic surfactant is awater soluble polyoxyethylene monoester of sorbitol with a C10 to C18fatty acid, marketed commercial under the Tween trademark. The Tweensurfactants are mixtures of C10 to C18 fatty acid esters of sorbitol(and sorbitol anhydrides), consisting predominately of the monoester,condensed with about 10-30, preferably about 20, moles of ethyleneoxide.The fatty acid (aliphatic hydrocarbonyl monocarboxylic acid) may besaturated or unsaturated, e.g., lauric, palmitic, stearic, oleic acids.Polysorbate 20 (e.g., Tween 20) is especially preferred and is commonlyreferred to as polyoxyethylene (20) sorbitan monolaurate. The nonionicsurfactant constitutes about 0 to 50% by weight and preferably 0.5 to40% by weight of the liquid composition.

The liquid whitening composition of the present invention may alsocontain a flavoring agent. Flavoring agents that are used in thepractice of the present invention include essential oils as well asvarious flavoring aldehydes, esters, alcohols, and similar materials.Examples of the essential oils include oils of spearmint, peppermint,wintergreen, sassafras, clove, sage, eucalyptus, marjoram, cinnamon,lemon, lime, grapefruit, and orange. Also useful are such chemicals asmenthol, carvone, and anethole. Of these, the most commonly employed arethe oils of peppermint, spearmint and wintergreen. The flavoring agentis incorporated in the whitening liquid composition of the presentinvention at a concentration of about 0.0 to about 2% by weight andpreferably about 0.1 to about 0.5% by weight.

A sweetening material may also be employed as an alternative orcomplement to the flavoring material. Suitable sweetening agents arewater soluble and include sodium saccharin, sodium cyclamate, xylitol,perillartien, D-tryptophan, aspartame, dihydrochalcones and the like, inconcentrations of about 0.01 to about 1% by weight. Sodium saccharin ispreferred.

Other ingredients which are included in the liquid whitening compositioncomprise materials commonly used in the oral care formulations. Theseinclude: antimicrobial agents, e.g., Triclosan, chlorhexidine, copper-,zinc- and stannous salts such as zinc citrate, zinc sulphate, zincglycinate, sodium zinc citrate and stannous pyrophosphate, sanguinarineextract, metronidazole, quaternary ammonium compounds, such ascetylpyridinium chloride; bis-guanides, such as chlorhexidinedigluconate, hexetidine, octenidine, alexidine; and halogenatedbisphenolic compounds, such as 2,2′methylenebis-(4-chloro-6-bromophenol); antiinflammatory agents such asibuprofen, flurbiprofen, aspirin, indomethacine; anticaries agents suchas sodium-, calcium-, magnesium- and stannous fluoride, aminefluorides,disodium monofluorophosphate and sodium trimetaphosphate; plaque bufferssuch as urea, calcium lactate, calcium glycerophosphate and strontiumpolyacrylates; vitamins such as Vitamin C; plant extracts; desensitizingagents, e.g., potassium citrate, potassium chloride, potassium tartrate,potassium bicarbonate, potassium oxalate, potassium nitrate andstrontium salts; agents effective against dental calculus such aspyrophosphate salts including the mono, di, tri and tetra alkali metaland ammonium pyrophosphate and tripolyphosphate salts; biomolecules,e.g., bacteriocins, antibodies, enzymes such as papain, glucoamylase;opacifying agents, pigments, coloring agents and fluoride ion providingsalts having anticaries efficacy such as sodium fluoride, potassiumfluoride, a tin fluoride such as stannous fluoride.

The liquid whitening compositions of the present invention are preparedby adding and mixing the ingredients of the composition in a suitablevessel such as a stainless steel tank provided with a mixer. In thepreparation of the liquid whitening composition, the ingredients areadvantageously added to the mixer in the following order: liquidanhydrous silicone based pressure sensitive polymer, peroxide whiteningagent, adhesion enhancing agent and any desired flavoring or sweetener.The ingredients are then mixed to form a homogeneousdispersion/solution. The moisture content of the tooth whiteningcomposition will be about 0.05% by weight to about 10% by weight, andpreferably about 2% by weight to about 8% by weight. The viscosity willbe about 50,000 cps to about 900,000 cps and preferably about 200,000cps to about 600,000 cps.

The present invention is illustrated by the following examples but isnot to be limited thereby.

EXAMPLES 1-4

The formulations in the following Table 1 were formed by adding thesilicone hydrophobic polymers Dow Corning Q7-9120 and Dow Corning 8-7016in a dimethicone solvent to a Brogli mixer. These two components weremixed for 30 minutes at high speed without vacuum. Sodium saccharin wasadded and mixing continued for 3 minutes at high speed without vacuum.The COP Plastigel 5 was then added and mixing continued for 10 minutesat high speed without vacuum. The Polyplasdoxyl XL10, 35% hydrogenperoxide peralkali and flavor were added and mixed on a low speedwithout vacuum for 5 minutes. Full vacuum then is applied and theformulation is mixed at high speed for an additional 15 minutes.

TABLE 1 Example 1 Example 2 Example 3 Example 4 Ingredient (Wt. %) (Wt.%) (Wt. %) (Wt. %) Dow Corning 30.0 30.0 30.0 30.0 8-7016 Dow Corning20.0 16.46 — 20.0 Q7-9120 Plunacare — — — 0.05 L 1220 Polyplasdone 25.025.0 25.0 25.0 XL-10 COP Plastigel 5 20.1 15.5 11.91 (Lyne Labs) 35%Hydrogen 4.0 12.14 44.1 12.14 Peroxide Peralkali Sodium Saccharin 0.30.3 0.30 0.30 VW Mint Flavor 0.6 0.6 0.6 0.60 Viscosity cps 180,000180,000 270,000 360,000

The formulations of Examples 14 have viscosities of 180,000 cps to360,000 cps. These formulations were found to have a workableconsistency in being applied to a tray and in adherence to teeth. Therealso is a low loss of formulation from the tray by the natural flushingaction of saliva.

EXAMPLE 5

The formulation of Example 3 was tested in vitro against a hydrophiliccommercial tooth whitening product. Six naturally stained prophied humanteeth were placed into two preformed thermoplastic trays, custom fittedto the teeth. In one tray was the formulation of Example 3 along with 3ml of saliva and in the other tray was the commercial product and 3 mlof saliva. The saliva is added to replicate mouth conditions. Theformulation of Example 3 and the commercial product were tested. TheExample 3 formulation and the commercial product were placed in separatetrays with the teeth for a period of 1 hour. There were 2 applicationsof the formulation and the product to the teeth. After each 1 hourperiod the teeth were rinsed with deionized water and maintained incontact with deionized water. There was a period of 10 minutes betweeneach treatment.

Table 2 gives the data from statistical analysis of the bleach action onthe test teeth as noted by the color change after 2 treatments for 1hours each. The tests were conducted on a Minolta CR-321 chromometerbased on initial L, a and b CIELAB values. The L, a and b values weremeasured four times at differing locations on the surface of the teeth.The average initial and the final chromometer were used to calculatedelta E according to (formula). The final delta E was the average overall observations after the rejection of outliersusing the Students test(95% confidence level). The product of Example 3 produces the greatercolor change to the teeth.

TABLE 2 Color Change after 5 Treatments (15 hours) Product ΔL Δb ΔECommercial 4.0 −4.4 6.4 Example 3 6.1 −7.0 9.5

Table 3 shows the consumption of peroxide during a 3 hours test. Thecommercial aqueous hydrophilic product consumed 26.7% of the peroxidewhile the hydrophilic product of Example 3 consumed only 8.9% of theperoxide.

TABLE 3 % Peroxide consumption after 3 hours Initial HP *Final HP % HPProduct Concentration (%) Concentration (%) Consumed Commercial 3 2.226.7 Example 3 4.5 4.1 8.9

The net result is that the hydrophilic formulation consumes lessperoxide to yield more stain removal. If treatments are continued formore than 3 hours there will be more peroxide available (higherconcentration) to remove stains and to whiten teeth.

1.-14. (canceled)
 15. A dental tray for treating teeth with a whiteningformulation comprising a dental tray formed to substantially cover thefront and a rear surface of at least one tooth, said dental traycontaining a substantially non-water soluble whitening formulationhaving a viscosity of about 50,000 cps to about 900,000 cps comprising ahydrophobic polymer that is a condensation product of a silicone resinand an organosiloxane, wherein the polymer is comprised of about 50 to70 parts silicone resin to 30 to 50 parts organosiloxane polymer.
 16. Adental tray as in claim 15 wherein said substantially non-water solublewhitening formulation has a viscosity of about 200,000 cps to about600,000 cps.
 17. A dental tray as in claim 15 wherein said substantiallynon-water soluble whitening formulation has substantially the followingformula: Component Content Hydrophobic Polymer   1 to 80 wt % AdhesiveEnhancing Agent   0 to 20 wt % Peroxide Whitening Agent 0.5 to 50 wt %Surfactant   0 to 50 wt % Flavor  0.1 to 1 wt % Other Agents   0 to 10wt %


18. A dental tray as in claim 17, wherein said hydrophobic polymer has aconcentration of about 15 to about 40 weight %.
 19. A dental tray as inclaim 17, wherein said adhesive enhancing agent has a concentration ofabout 2 to 15 weight %.
 20. A dental tray as in claim 17, wherein saidperoxide whitening agent has a concentration of about 10 to 40 weight %.21. A dental tray as in claim 17, wherein said peroxide whitening agenthas a concentration of about 15 to about 35 weight %. 22.-23. (canceled)24. A dental tray as in claim 15, wherein the hydrophobic polymer is acondensation product comprised of about 50 to 70 parts silicone resin to30 to 50 parts organosiloxane polymer.
 25. A dental tray as in claim 17,wherein said adhesive enhancing agent is selected from a groupconsisting of waxes, nonionic polymers of ethylene oxide and nonioniccopolymers of ethylene oxide and propylene oxide.